In 1982, a Maine girl named Samantha Smith wrote a letter to Yuri Andropov, pleading for peace. This led to her being invited by the Soviet leader to visit the U.S.S.R. The media coverage of her trip was closely monitored by then-8-year-old Elliott Holt, growing up in Cold War-era Washington.

Holt apparently has been thinking about this incident ever since, as it forms the basis for her debut novel, “You Are One of Them,” a genre-bending story of female friendship with a macho streak of spy-novel intrigue.

Holt’s narrator is Sarah Zuckerman, a girl damaged by her younger sister’s death and her parents’ divorce. Then, fortune delivers a fresh-faced new neighbor, Jennifer Jones. “I’d never had a best friend,” Sarah explains, “but I didn’t tell Jenny that. I didn’t tell her that until she came along, I’d never felt like I belonged anywhere.”

As her mother and the media obsess over images of nuclear disaster and intimations of war, Sarah writes a letter to Andropov. Jenny says she’ll write one, too. A few months later, The Washington Post calls the Jones’ house; Jenny’s letter has been published in Pravda. Andropov writes her back: “The Soviet people are for friendship and peace.” Soon Jenny is an international celebrity, on her way to the U.S.S.R. with her family.

To Sarah’s bewilderment and despair, there is never any mention of her letter.

The plot from there is tricky. Suffice it to say that after the Joneses return, the girls’ friendship is never the same, and later the whole family is killed in a plane crash. Sarah is overwhelmed by confusion and loss.

Ten years later, she receives a letter from Russia suggesting that Jenny may be alive. The second half of the book takes place in Moscow, where Svetlana, the author of the letter, was Jenny’s designated “friend” during the 1983 publicity trip. To unscramble the truth takes Sarah longer than she expected, but her months in the frozen city with its endless drinking, smoking and cynicism make for a quick read. The ambiguous resolution won’t satisfy all readers, but it is true to Holt’s theme: There are things, and people, we can never absolutely know.